In general, shaving razors of the wet shave type include a cartridge or blade unit with at least one blade with a cutting edge, which is moved across the surface of the skin being shaved by means of a handle to which the cartridge is attached. The cartridge may be mounted detachably on the handle to enable the cartridge to be replaced by a fresh cartridge when the blade sharpness has diminished to an unsatisfactory level, or it may be attached permanently to the handle with the intention that the entire razor be discarded when the blade or blades have become dulled (i.e., disposable razor). The connection of the cartridge to the handle provides a pivotal mounting of the cartridge with respect to the handle so that the cartridge angle adjusts to follow the contours of the surface being shaved. In such systems, the cartridge can be biased toward a rest position by the action of a spring-biased plunger (a cam follower) carried on the handle against a cam surface on the cartridge housing.
Razor cartridges usually include a guard which contacts the skin in front of the blade(s) and a cap for contacting the skin behind the blade(s) during shaving. The cap and the guard aid in establishing the so-called “shaving geometry”, i.e., the parameters which determine the blade orientation and position relative to the skin during shaving, which in turn have a strong influence on the shaving performance and efficacy of the razor. The cap and the guard may aid in establishing the exposure of the blades. The blade exposure is defined to be the perpendicular distance or height of the blade edge measured with respect to a plane tangential to the skin contacting surfaces of the blade unit elements next in front of and next behind the edge. Therefore, for a three-bladed blade unit, the exposure of the first or primary blade is measured with reference to a plane tangential to the guard and the edge of the second blade, and the exposure of the third or tertiary blade is measured with reference to a plane tangential to the edge of the second blade and the cap.
The minimum acceptable exposure may be influenced by other blade unit dimensions, such as the distance from the skin engaging surface of the guard to the edge, i.e. “the span” of the primary blade. As referred to herein, “the span” means the distance from the blade edge to the skin contacting element immediately in front of that edge as measured along a tangent line extending between the said element and the blade edge. The guard may include a generally rigid guard bar that may be formed integrally with the housing or platform structure, which provides a support for the blades. Guards may also include skin stretching elements made from various types of elastomeric materials that are intended to stretch the skin and/or align hair in front of the blade.
Safety razors having cartridges with several blades have in recent years been sold in very large numbers and are generally acknowledged to give a better quality of shave, especially in terms of closeness, than single bladed razors. A blade unit having many blades can produce a closer shave than a similar blade unit with only one or two blades. However, closeness of shave obtained is only one parameter by which razor users judge the performance of a razor. Comfort is another important characteristic to consider. For example, many consumers describe themselves as having sensitive skin, which is prone to nicks, cuts and irritation. Discomfort during a shave, often described by shavers as a “pull & tug” sensation is caused by the nerves around the follicle being stimulated. This nerve stimulation can happen by moving the hairs, pulling and/or cutting the hairs and by dragging the razor cartridge over the surface of the skin.
Additionally, many consumers suffer from acne and/or pseudofolliculitis barbae (PFB) that make shaving uncomfortable. PFB or shaving bumps is a foreign body inflammatory reaction involving papules and pustules. It is a common dermatologic condition principally affecting adult men who have naturally coarse or tightly curling hair, particularly those who shave closely on a regular basis. The leading edge of closely cropped facial hair re-entering the epidermis of the skin or transecting the wall of the hair follicle results in localized inflammatory reactions over the affected site. The process can lead to secondary skin infections and, in severe cases, permanent scarring. Accordingly, what is needed is a shaving razor cartridge that provides a more comfortable shave and/or decrease skin issues caused by shaving the face and body (e.g., PFB, irritation, redness, razor bumps, ingrown hairs, acne etc.).